Anyways Superman can fly so fast he can cause the planet to reverse direction while being careful enough to knock it's axis funny and send it hurling through space, and rewind time so he can save Lois.
lol. On to some more serious stuff;
Also it depends on where and what version of Superman you're talking about. There is times when Superman's powers are seemingly unlimited: he's traveled millions of light-years in brief periods of time; he could dive into stars unharmed; he could travel through time by moving at speeds faster than light; and he could move planets and lift any weight. He could even vibrate his body so fast, the vibrations rendered him "invisible" to the human eye, similar to "The Flash." On Earth, for some reason Flash [faster than light speed] smokes Supes flying or running or whatever, but it seems this only holds until Superman steps into the vaccuum of space, where he can basically make up his own rules.